William e



(No Model.)

' W. R. COLE.

MICROPHONE TRANSMITTER. No. 352,806. Patented Nov. 16, 1886.

In?! for.

. To all whom it may concern.-

UNITED STATES PATENT. OFFICE WILLIAM E. coLE, OE DETROIT, MICHIGAN, ASSIGNOE TO HIMSELF AND FRANK e. SMITH AND GEO. w. MOORE, TRUSTEES, OF SAME rLAcE.

MICROPH NE-TRANSMITTER.

' SPECIFICATION forming part of Letters Patent No. 352,806, dated November 16, 1886.

Application filed May 27, 1886.

Be it known that I, WIL IAM R. COLE, of Detroit, in the county of Wayne and State of Michigan, have invented new and useful Improvements in Microphone-Transmitters; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing, which forms a part of this specification.

This invention relates to certain new and useful improvements in the construction and operation of microphone-transmitters that will be very sensitive to the'human voice, while it will not be materially affected by outside influences or by jars and concussions, and at the same time be simple in construction and adjustment.

Y of the diaphragm B, which is secured to a rubber ring, B, in the usual way.

0 is a flexible bar, preferably of metal, with an electrode, D, secured at each end thereof.

E is a metallic contact-point secured to the center of the bar and resting upon the center of the diaphragm.

F F are electrodes, One'being fastened to the end of each of the adjusting-screws G G, which are supported by brackets H H, which are secured to the rear face of the base A.

I I are small-guide-plates to support the bar 0. This bar 0 is placed parallel with the diaphragm, and preferably in a horizontal posinon.

The operation of this device is as follows:

When the diaphragm is caused to vibrate, a.

pressure is brought to bear against the bar C (which is slightly curved toward the diaphragm) through the metallic contact-point, the vibration of the diaphragm to spring, straighten, or curve, thus bringing different pressures to bear upon the electrodes at the ends of the bar, such varying pressures being caused by the varying strength of the soundwaves and their influence upon the vibrations of the diaphragm. The electrodes F F are made adjustable bythe set-screws, in order to secure the required adjustment.

It is not absolutely necessary to have an electrode and adjusting-screw at each end of the Serial N 0. 203,387. (No model.)

spring-bar, as one electrode and screw at either end of the bar, with the opposite end resting against a post, will answer very well; but it is preferable to have the two, as described, as the current in passing through is varied much more. The contact-point E is simply to prevent the spring-bar from resting to too great an extent upon the diaphragm. The current passes in through the bracket or post H at one end, and through the electrodesand out at the opposite end.

While the spring-bar is preferably made of metal, other suitable materials may be employe.dsuch as whalebone, for instancehaving a fine wire connected to it and connecting the electrodes D D. The guide posts or supports I-I may be dispensed with, and thespringbar may be supported by notches in the electrodes F F, in which case the ends of the bar should slightly project through the electrodes D D, to form a bearing to rest in the notches.

What I claim as my invention is- 1. In combination with a diaphragm, ahorizontal curved spring-bar with an electrode at one end, such bar lying in a plane substantially parallel with the rear face of the diaphragm and with its center in contact with said diaphragm, substantially as described.

2. In combination with a diaphragm and spring-bar having an electrode at both ends thereof, one or more adjustable electrodes carried by adj listing-screws and arranged in contact with the electrodes on said bar, substantiall y as and for the purposes specified.

3. In combination with a diaphragm,springbar, and electrodes at each end of said bar, as described, guide posts or plates supporting such spring-bar, substantially as set forth.

4. A microphone'transmitter consisting of the following elements: a base, a diaphragm, a curved spring-bar centrally in contact with such diaphragm and carrying electrodes at both ends of such bar, and one or more adjustable electrodes, the parts being constructed, supported, and arranged with relation to each other substantially as and for the purposes described.

-w. R. ooLE.

Witnesses:

H. S. SPRAGUE,- CHAS. THURMAN. 

